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Key Question 1: What is a coastal system and what are the
dynamics of coastal environments?

The Coastal System
The coast is the interface between land and sea. One way to study the coast is to view
it as a system. The coast is an open system. Energy inputs from…

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steepest gradient. This produces a zig-zag
movement of sediment along the beach
known as longshore drift. The action of
waves constantly moves and sorts different
sized material beach material..The action of
longshore drift sorts beach material, due to
the amount of energy required to move
sediments. Larger particles will need…

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High and low energy coasts in the UK.

High energy coasts are ones in which wave power is strong for a significant proportion
of the year. The distribution of these coasts is largely controlled by the climate and
direction they face. Strong winds capable of generating the largest waves are…

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longest fetch. Maximum wave heights decrease from west to east and from north to
south across the British Isles away from exposure to the open ocean and onshore
westerly winds. Fetch is the limiting factor for the height of waves generated by
easterly winds in the North Sea. No matter…

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Dynamic equilibrium in the coastal system
Why do some coastlines erode away? Why do some grow?

All beaches exist in a dynamic equilibrium involving four factors:

1. The supply of sand

2. The energy of the waves

3. Changes in sea-level

4. The location of the shoreline

It is the…

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will return sand to the beach. As mentioned earlier, sand effectively armors the shore
against wave attack and erosion.

It is only because most people see coasts as broadly stable over the human life span
that they do not recognise that coastal change is constant and that; over the long-…

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3. Dynamic equilibrium
Like meta stable equilibrium, this too involves a change in equilibrium conditions but
in a much more gradual manner. A good example is the response of coasts to the
gradual rise in sea levels that were experienced through the twentieth century as a
result of climate change.…

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Wave types

Waves are undulations of the
water surface caused by winds
blowing across the sea. They
consist of orbital movements of
water molecules which diminish
with depth. In the open ocean wind
rippling water can lead to growth
into recognisable waves. The
circular motion of waves at the
surface…

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Fetch, wind direction and wind strength are the main factors determining the
height and energy of breaking waves. Fetch is the distance of uninterrupted
water surface over which the wind has blown to form the waves. The loner the
length of open water over which the winds travel, the longer…